A blog about some of the Antarctica Weddell seal population study field research work and outreach efforts during the Weddell seal pupping season in the Erebus Bay region of Antarctica's Ross Sea. Weddell seal images and recordings obtained under NMFS Permit Nos. 1032-1917, 17236, and 21158. More information at http://WeddellSealScience.com

18 December 2017

An Extraordinary Erebus Bay Weddell Seal Pupping Season!

Thanksgiving brought not only a replenishing break from the field and camp life for the crew, but also a much needed break in the weather. From turkey day onward, conditions and visibility remained decent enough to catch up on things and finish out the season strong.

One of our primary goals each season is to tag all the pups in the study area. This allows us to keep track of which mothers give birth to which pups, as well as the survival and reproduction of each pup into the future.

The final tally of tagged pups this season was in the mid 700s! We were also able to finish up the re-weighing of the pups selected for the mass study, which is focused on understanding the investment of moms in their pups during the nursing period and what that might mean for the future of that pup. This is the third and last re-weighing of these pups, representing their weaning weight at 35 days old (right around the time the mom's wean their pups and leave them). We've nearly forgotten what the freshly-born pups used to look like now that they have tripled their body mass and have molted their lanugo (fluffy pup fur) in favor of a smooth, finely-patterned coat.

The pups this season averaged 66.92 lbs. at birth and 214.4 lbs. at weaning. We collected mass data on 135 pups and weighed a total of 54,457 lbs. of seal pups! As part of this study, we used photogrammetry to estimate the mother's mass (turns out it's really hard to get a 800 lb. animal on a weigh scale) which entails taking 360 degrees-worth of photos around the mom. Lastly, we completed 6 surveys of the study area, where we record every seal we can find on top of the ice to estimate the population size. During one survey we surveyed 1,570 tagged seals which exceeds the greatest number we sighted during any one survey in the past 10 years! We were able to visit the hard to reach North Base and South Base seal colonies (these are located in areas that require a good hike) and flew our 2nd and last mission to the White Island colony, where we tagged 6 pups during the season.

Our huts were pulled off the ice on Dec. 9, and saying goodbye to the seals and our Big Razorback home of 2 months (really it is the seals home and we are the visitors) is always a melancholy moment. We spent 3-4 days pulling all the bamboo flagged routes across the study area, collapsing many miles of roads into several bundles of flagged bamboo poles.

Thanks to a solid crew and the incredible support we received from the workforce in McMurdo, we had a very successful season. Half of our crew (Alissa, Aubrey, and Thomas) redeployed for New Zealand on Dec. 9, and the rest (Kaitlin, Shane, and Jesse) remained on station to clean, sort, organize, inventory, and return field gear until Dec. 15. Thanks to all our blog readers and we'll see you next season!